The Sith Stalker Armor represented a form of armor that was cybernetically attached to its user, covering the entire body with the exception of the arms. Displaying design elements reminiscent of both Mandalorian and Ubese armor, this Sith stalker armor presented a terrifying and macabre image. Historically, this armor type was a favorite among brutal Sith assassins, who inspired great fear within both the Sith and Jedi orders.

Sith stalker armor was grafted, often painfully, onto the body to transform dark side disciples into formidable Sith assassins. The armor's intimidating design was specifically intended to instill fear in any opponent.
Instead of gauntlets, the armor replaced most of the hands with prosthetic replacements, though some flesh remained, allowing the wearer to utilize Force lightning in battle without fear of negative repercussions. The prostheses included metal claws attached to the fingertips. Despite their noticeable length, the claws did not seem to impede the wearer, likely due to extensive practice. Head protection was provided by a close-fitting helmet that completely covered the head. The helmet's faceplate resembled a Ubese bounty hunter mask incorporating a Mandalorian-style T-shaped visor. The armor also appeared to integrate a breathing apparatus, though the wearer seemed to control the mechanism, rather than it being automated, evidenced by the forced and irregular breathing pattern.
A high metal collar protected the neck, connecting to a form-fitting pauldron that guarded the right shoulder. Angular metal plates, grafted onto the skin and connecting to the largely prosthetic right hand, shielded the right forearm. The left arm and shoulder remained uncovered. The chest was protected by flexible, ribbed armor plates. The armor incorporated several leather belts, used for carrying lightsabers taken from vanquished foes.
Below the belts, another set of ribbed plates formed a girdle, protecting the waist and groin. The type of leg protection used is obscured by a tattered, floor-length combat skirt. Underneath the plates and skirt, the wearer wore a tight-fitting black bodysuit, seemingly made of leather. This suit was specially designed not to hinder the wearer's physical strength, agility, or Force abilities.

During his mission to Kashyyyk during the Great Jedi Purge, Darth Vader's secret apprentice, Galen Marek, known as Starkiller, donned the Sith Stalker Armor while experiencing a Force vision where he killed a Jedi Knight. He later encountered the same armor while battling a vision of himself wearing it within the Jedi Temple on Coruscant.

In the dark side ending of Star Wars: The Force Unleashed, Galen Marek suffered severe injuries at the hands of Emperor Palpatine, but his body was reconstructed in a manner analogous to Darth Vader's transformation into the Emperor's Sith apprentice.
This costume features six lightsabers on Marek's belt: his new Sith lightsaber, characterized by three spiked blade guards; his original lightsaber that he constructed under Vader's guidance; Rahm Kota's lightsaber, which also served as Marek's second; one half of the lightsaber formerly wielded by Darth Maul; Darth Vader's lightsaber; and the upper section of Kazdan Paratus' dual bladed lightsaber staff (the dual blades are exclusive to the Wii and DS versions).
Upon completing the game and selecting the dark side ending, players gain the option to replay the game while wearing the Sith Stalker Armor. Enhanced versions of the armor appear in the Ultimate Sith Edition of the game. During the Tatooine mission, the player wears a set called the "Desert Survival Gear," which includes Tusken Raider attire worn over the armor. In the Hoth mission, a variant known as the "Dark Lord's Armor" is featured. According to its description, it was heavily influenced by Vader's armor and incorporated numerous modifications from the standard Sith Stalker Armor. The original skin-tight leather bodysuit and ribbed abdominal plates are replaced by a full body-suit constructed from the same quilted material as Vader's armor, along with similar-looking pectoral armor. The hands are gloved, and the helmet features an outward-sloping metal plate that protects the rear and sides of the neck, mimicking the silhouette of Vader's helmet.